It is covered with numerous large papillae, and forms, like the trunk of the elephant, an admirable organ for the examination and prehension of food.
Most remarkable is its resemblance to the adult form of the Wheel animalcules, or Rotifera, which retain the prae-oral ciliated band as their chief organ of locomotion and prehension throughout life.
Very often one or other of the appendages may be modified for prehension, the seizing of prey or the holding of a mate.
In a few Ostracoda, by a rare exception, the masticatory process is reduced or suppressed, and the palp alone remains, forming a pediform appendage used in locomotion as well as in the prehension of food.
To these succeeded forms where the down had developed into body feathers for warmth, not flight, whilst the fore-limbs had become organs of prehension, the hind-limbs of progression.